pgsql: Add option -N/--no-sync to pg_upgrade

Add option -N/--no-sync to pg_upgrade

This is an option consistent with what the other tools of src/bin/
(pg_checksums, pg_dump, pg_rewind and pg_basebackup) provide which is
useful for leveraging the I/O effort when testing things.  This is not
to be used in a production environment.

All the regression tests of pg_upgrade are updated to use this new
option.  This happens to cut at most a couple of seconds in environments
constrained on I/O, by avoiding a flush of data folder for the new
cluster upgraded.

Author: Michael Paquier
Reviewed-by: Peter Eisentraut
Discussion: https://postgr.es/m/YbrhzuBmBxS/DkfX@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/3d5ffccb6df323f528cf870c26d0d0517ffe3eaa

Modified Files
--------------
doc/src/sgml/ref/pgupgrade.sgml | 16 ++++++++++++++++
src/bin/pg_upgrade/option.c     |  9 ++++++++-
src/bin/pg_upgrade/pg_upgrade.c | 13 ++++++++-----
src/bin/pg_upgrade/pg_upgrade.h |  1 +
src/bin/pg_upgrade/test.sh      |  2 +-
src/tools/msvc/vcregress.pl     |  4 +++-
6 files changed, 37 insertions(+), 8 deletions(-)